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Re: Garage door detail

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T wrote:
> 
> Subject: Garage door detail
> 
> >...1997 (many of you may also have gotten it).  It is a garage door detail,
> which consists of a GLB spanning the garage opening, supported by two very
> narrow (16" min) walls, which are sheathed on two sides. The ply sheathing
> is nailed to the GLB in a grid pattern.  Tiedown straps are added between
> the GLB and the walls, with HD's as the footing.
> 
> >My initial thoughts on this are:
> 
> >We could resolve the moment at the GLB/wall connection by distributing the
> load to the nails in the grid pattern (this was a basic statics problem in
> school). The nails would all be in shear.
> 
> We could determine the uplift force by resolving the moment into a couple
> (another basic statics problem). We could use standard Simpson products (or
> equal) for the straps and holdowns.


> 
> What we are doing is creating a wood moment frame. Is this wise?? If wood,
> over time, shrinks, or takes on a permanent deflection, wouldn't the nails
> lose their shear resistance capacities?
> 
> Talk to me, people
> 
> Kate O'Brien, P.E.
> Simi Valley, CA
> 
> Assuming that this detail is meant to be a portal frame!
> 
> The main shrinkage will be across grain.  The glulam and the plywood should
> show little shrinkage.  The amount of nail grip loss will therefore be
> minimal.  If that is considered a problem then allow for it in the treatment
> factors Kt or Kst.
> 
> I have a problem with the base detail.  With such a short "wall" the moment
> transfer to the foundation is going to be relatively high.  The detail as
> shown would not adequate for the moments possible.  Alternatively the lower
> connection should be detailed as a "pinned" condition.  Also, serious
> anchors may be needed into the foundation and the glulam connection
> depending on the load accumulation at this joint.
> 
> In order to reduce the load(s) to such a portal, consideration of the
> supported floor to act as a diaphragm might work.
> 
> Thor Tandy  P.Eng
> Victoria  BC
> 
I need help.  If the moment connection is between the GLB and the
"Wall", I considered that only a pin may exist at the base of this
frame.